Although uncommon, primary appendiceal neoplasms often result in clinical symptoms that may lead to abdominal imaging. Acute appendicitis from luminal obstruction is the most common manifestation for most tumor types. Other manifestations include intussusception, a palpable mass, gastrointestinal bleeding, increasing abdominal girth (from pseudomyxoma peritonei), and secondary genitourinary complications. Asymptomatic appendiceal neoplasms may be discovered incidentally. Mucoceles from either benign or malignant mucinous neoplasms represent the majority of appendiceal tumors detected at imaging but are the least likely to manifest as appendicitis. Pseudomyxoma peritonei is a common manifestation of mucinous adenocarcinoma. Colonic-type (nonmucinous) adenocarcinoma of the appendix is much less common than mucinous tumors and typically manifests as a focal mass without mucocele formation. Carcinoid tumor is the most common appendiceal neoplasm but is less often detected radiologically because it is typically small and relatively asymptomatic. Goblet cell carcinoid tumor and non-Hodgkin lymphoma of the appendix are rare and usually infiltrate the entire appendix. Cross-sectional imaging, particularly computed tomography (CT), is effective in the evaluation of these neoplasms. CT appears to be the modality of choice whenever an appendiceal mass is suspected. CT will help rule out or confirm an appendiceal tumor and may suggest a more specific diagnosis.

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Primary carcinoma of the gallbladder is an uncommon, aggressive malignancy that affects women more frequently than men. Older age groups are most often affected, and coexisting gallstones are present in the vast majority of cases. The symptoms at presentation are vague and are most often related to adjacent organ invasion. Therefore, despite advances in cross-sectional imaging, early-stage tumors are not often encountered. Imaging studies may reveal a mass replacing the normal gallbladder, diffuse or focal thickening of the gallbladder wall, or a polypoid mass within the gallbladder lumen. Adjacent organ invasion, most commonly involving the liver, is typically present at diagnosis, as is biliary obstruction. Periportal and peripancreatic lymphadenopathy, hematogenous metastases, and peritoneal metastases may also be seen. The vast majority of gallbladder carcinomas are adenocarcinomas. Because most patients present with advanced disease, the prognosis is poor, with a reported 5-year survival rate of less than 5% in most large series. The radiologic differential diagnosis includes the more frequently encountered inflammatory conditions of the gallbladder, xanthogranulomatous cholecystitis, adenomyomatosis, other hepatobiliary malignancies, and metastatic disease.

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Caroli's disease and its complications have overlapping radiologic appearances that reflect the underlying pathology of fibrosis, ductal dilatation, cholangitis, stone formation, and malignancy.

Non-breath-hold MR cholangiography is a reliable method for depiction of the biliary system.

CT findings strongly suggest the presence of underlying neoplasm in the majority of patients with secondary appendicitis.